Sorry but it's a fail, your probe is not fast enough.
As I said, this is probably the hardest challenge of team Frontier, so I really advise trying the others first. Especially that we are currently reevaluating the criteria that determines wether or not the challenge is a success. Because Mars orbit is no longer circular, we can't simply evaluate the speed when the probe crosses Mars orbit now.
Also, I suggest to read the tutorial pinned in this section for this challenge, there are a lot of useful informations in it. This is an optimization challenge, if you try building a launcher without having a clear idea about what you are doing, there's a high risk to fail.